Infrared radiation accounts for approximately 50% of the solar spectrum. Specifically, the near-infrared (NIR) spectrum, ranging from 760 nm to 2500 nm, is primarily responsible for solar heat gain, increasing indoor temperatures and reducing heating and cooling efficiency. To address this issue, we developed a highly transparent thermo-shielding flexible film that maintains a high transmittance of the visible region (T = 80%) while reducing the transmittance of the NIR region (T ≈ 0%). NIR-absorbing indium tin oxide (ITO) nanocrystals were coated onto polyethylene terephthalate (PET) films, and both films were sandwiched to improve the NIR absorption properties and protect the nanocrystal film layer. The fabricated films were applied to a model house and decreased the indoor temperature by approximately 8°C. Our study demonstrates that energy consumption can be reduced by ITO nanocrystal-coated flexible films, with potential implications for the smart window and mobility markets.

촉매 1,8-diazabicyclo[5,4,0]undec-7-ene(DBU)를 이용하여, poly(vinylidenefluoride-co-chlorotrifluoroethylene) P(VDF-co-CTFE) 고분자와 methacrylic acid (MAA)를 반응시켜, P(VDF-co-CTFE)-MAA 공중합체를 제조하였다. 또한 P(VDF-co-CTFE)-MAA와 2-sulfoethyl methacrylate (SEMA) 단량체를 4’,4’-azobis(4-cyanovaleric acid) (ACVA) 개시제 하에서 자유 라디칼 중합하여 수소 이온 전도성 막을 제조하였다. SEMA 함량이 많아짐에 따라 술폰산 그룹이 증가하였다. SEMA 함량이 50%일 때 최대 이온교환 용량값이 0.82 meq/g에 도달하였으며 이는 함수량 결과와 일치하였다. 또한, SEMA 함량이 50%일 때 수소이온 전도도가 0.041 S/cm까지 도달하였다. 이러한 결과는 분리막에서 SEMA 함량이 증가할수록 수소 이온을 전달시킬 수 있는 이온그룹이 증가하기 때문이다.